1. Field of the Invention
The present invention relates to a process gas supply unit used in a semiconductor manufacturing process and, more particularly to a process gas supply unit provided with components parts such as a process gas supply valve, a purge valve, a check valve, a vacuum valve, a mass flow controller, a regulator, a filter, and the like.
2. Description of Related Art
A process gas supply unit supplies process gas such as etching gas in a semiconductor manufacturing process. In this semiconductor manufacturing process, a cut sheet process for processing wafers one by one is being substituted for a batch process for processing plural wafers at the same time. The cut sheet process requires a small-sized process gas supply unit.
To make a small-sized process gas supply unit, the applicant of the present invention has proposed a process gas supply unit as disclosed in Japanese Patent No. 2,568,365 wherein a supply valve, a purge valve, and a vacuum valve are fixed with bolts from above on a module block acting as a manifold.
FIG. 15 shows a structure of the process gas supply unit using the manifold. This unit is an embodiment of a flow circuit diagram shown in FIG. 16, which is described below.
In FIG. 16, a process gas is supplied from a left end of the supply unit and discharged from a right end of same. A manual valve 1, a check valve 2, and a regulator 3 are connected in order. The regulator 3 is connected to an input valve 5. A pressure gauge 4 is connected in the flow passage between the regulator 3 and the input valve 5. The input valve 5 is connected to an input port of a mass flow controller 8 to which a purge gas source is connected through a purge valve 6 and a check valve 7.
An output port of the mass flow controller 8 communicates with an output valve 10 and also to a vacuum pump which is a vacuum source through a vacuum valve 9. The output valve 10 is connected to a manual valve 11 whose exit port communicates with a vacuum chamber in the semiconductor manufacturing process.
Next, the process gas supply unit embodying the flow circuit diagram of FIG. 16 will be described referring to FIG. 15.
All of main devices are fixedly mounted on a mounting panel 12 with bolts. A bracket B1 connects the manual valve 1 to the panel 12. The manual valve 1 is provided, at either end, with pipes 1a and 1b and joints M. The pipe 1b and the joint M disposed in a downstream side of the manual valve 1 are connected to the check valve 2. A joint M and a pipe 3a connect the check valve 2 to the regulator 3. The regulator 3 is fixed on the panel 12 by a bracket B2 (whose structure is the same as the bracket B1).
On the right side of the regulator 3, a trifurcated pipe 5a and joints M connect the regulator 3 to a manifold C1, and a trifurcated pipe 4a connects to the pressure gauge 4. On an upper plane of the manifold C1, the input valve 5 and the purge valve 6 are mounted. A pipe 6a and a joint M connect the check valve 7 to a port of the manifold C1 for the purge valve 6. The check valve 7 is connected to a purge gas source not shown through a joint M. Here, the passage formed by the check valve 7 and the pipe 6a is provided on a plate A1.
The manifold C1 is fixed on the panel 12 through a plate A1 and is connected to a mass flow controller block D. A mass flow controller 8 is mounted on an upper plane of the mass flow controller block D. The right end of the mass flow controller block D is connected with a manifold C2 (whose structure is the same as the manifold C1). The vacuum valve 9 and the output valve 10 are mounted on the manifold C2. Then vacuum valve 9 is connected with the vacuum pump which is a vacuum source. The manifold C2 is fixed on the panel 12 through a plate A2 (whose structure is the same as the plate A1). Here, a flow passage extending from the check valve 7 is contiguous to a channel formed in the plate A2.
The manifold C2 is connected with the manual valve 11 through a joint M and a pipe 11a. The manual valve 11 is secured on the panel 12 by a bracket B3 (whose structure is the same as the bracket B1) and is connected at its right end with a vacuum chamber through a pipe 11b and a joint M.
The supply unit shown in FIG. 15 uses the manifold C1 on which the input valve 5 and the purge valve 6 are integrally mounted from above by fastening bolts. A supply unit could be reduced in size as compared with the supply unit in which all of the main devices are connected with each other through pipes. The supply unit shown in FIG. 15 is too big for recent process gas supply units which must be reduced in size and integrated. Many pipes and joints are required in the FIG. 15 supply unit design, needing large space and causing the generation of particles in many weld joint portions of the pipes. This generation of particles affects a yield of a semiconductor to be manufactured, which is an important problem.
In the FIG. 15 design, to detach the manifold C1 and the plate A1, on which the input valve 5 and the purge valve 6 are mounted, from the mounting panel 12, the mounting panel 12 must be turned over because the plate A1 is fixedly mounted on the panel 12 with bolts from below, thus requiring removal of all of the devices fixedly mounted on the panel 12. This is extremely inconvenient since the mounting panel 12 is generally fixed on a wall and the like in firm contact therewith to reduce an installing space for the process gas supply unit in the semiconductor manufacturing process. The same applies to the manifold C2 and the plate A2 on which the vacuum valve 9 and the output valve 10 are mounted.